Field of the Invention
The present invention relates to an antenna device and a portable electronic device.
Background Art
It is known that conventional GPS (global position system) schemes measure the longitude and latitude of a current location in accordance with GPS signals in GPS radio waves, which are received from GPS satellites via a GPS antenna. One example of such a GPS antenna is a patch antenna. There are also handy terminals equipped with GPS reception units that have a GPS antenna therein, and these terminals can detect current location.
Compound antennas, which are provided with a plurality of antennas for detecting radio waves of different frequencies, are also known. Japanese Patent Application Laid-Open Publication No. 2003-152445 discloses a compound antenna that has a patch antenna for transmission and reception of ETC (electronic toll collection system) or DSRC (dedicated short-range communications) signals and that receives radio waves of two different frequencies, for example. Japanese Patent Application Laid-Open Publication No. 2003-163531 discloses a compound antenna that has a patch antenna for transmission and reception of ETC or DSRC signals, a loop antenna for GPS signals, and a loop antenna for receiving radio wave beacons. This compound antenna receives three different frequencies.
There is demand for a GPS antenna to be provided in a handy terminal having a reader/writer for RFID (radio frequency identification)/NFC (near-field communication) signals. When a plurality of antennas are provided as in Patent Documents 1 and 2, however, the GPS antenna is disposed in the vicinity of the loop antenna (antenna coil) used for RFID, and the interference between these antennas degrades antenna performance characteristics such as directionality.
On the other hand, to ensure the performance of both antennas without interference, it is necessary to install the antennas in locations that are separated from each other at approximately λ/4 of a wavelength of the frequency being used, which hinders miniaturization of the handy terminal.